Effect of Regression of Enlarged Neck Lymph Nodes on Radiation Doses Received by Parotid Glands During Intensity-Modulated Radiotherapy for Head and Neck Cancer

Kuo, Yi Chun; Wu, Tong; Chung, Tao Sang; Huang, Kai; Chao, K.S. Clifford; Su, Wen Chuan; Chiou, Jeng Fong

doi:10.1097/01.coc.0000239093.95769.b3

Cited by 51 publications

(29 citation statements)

References 14 publications

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“…Decreased coverage of the target volume and increased doses to critical structure might be the consequence. In treatment with intensity-modulated radiotherapy (IMRT), where sharp dose gradients between the target and organs at risk require high precision of treatment [10,15,[17][18][19], replanning has been demonstrated to compensate these adverse effects of tumor shrinkage [8,13]. In-room imaging with soft-tissue contrast will allow us to observe such changes during radiotherapy and select patients in whom replanning might be necessary.…”

Section: Discussionmentioning

confidence: 99%

Nonrigid Patient Setup Errors in the Head-and-Neck Region

Polat¹,

Wilbert²,

Baier³

et al. 2007

Strahlenther Onkol

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Section: Discussionmentioning

confidence: 99%

Nonrigid Patient Setup Errors in the Head-and-Neck Region

Polat¹,

Wilbert²,

Baier³

et al. 2007

Strahlenther Onkol

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“…Robar et al [4] documented that both parotid glands showed a median translation of 0.85 mm per week, and glands shrank by 4.9% per week. In the study by Kuo et al [5], the lymph nodes in head and neck cancer underwent a volume reduction of more than 50% after 45 Gy of treatment, which may increase actual radiation doses to the parotid glands. These anatomical changes would probably cause overdose to the OARs and underdose to targets, which would negate the benefits of IMRT.…”

mentioning

confidence: 99%

Dosimetric variations of target volumes and organs at risk in nasopharyngeal carcinoma intensity-modulated radiotherapy

Zhang

M²,

Cao³

et al. 2012

The British Journal of Radiology

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Objective: The aim of this study was to evaluate the actual dose variability to the targets and organs at risk (OARs) during nasopharyngeal carcinoma (NPC) intensitymodulated radiotherapy (IMRT) and to investigate the significance of replanning. Methods: 11 NPC patients were included in this study. Each patient had both a planning CT and weekly repeated CT. Simulated plans that were generated by using the same beam configurations mapped to the repeated CT represented the actual delivered doses to the target volumes and OARs. An IMRT replanning was performed with the fifth week CT scan. Doses among the initial plan, the simulated plans and replanning were compared. Results: There were no significant dosimetric differences in the gross tumour volume, clinical target volume (CTV) 1 or CTV2 for either the simulated plans or the replanning compared with the initial plan. Dosimetric variability of both parotid glands and the brain stem were unique to each individual, and doses to the spinal cord were always maintained within the limit. Replanning in the fifth week had significantly decreased the doses delivered to both parotids (p-values of the mean dose were 0.015 and 0.026 for the left and right parotid, respectively), whereas it did not reduce the doses to the brain stem and spinal cord. There was no relationship between dose variability and weight loss. Conclusions: There are no significant dose changes for target volumes and spinal cord, and doses to the brain stem and both parotid glands changed individually during NPC IMRT. Replanning helps to spare bilateral parotids.

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“…Kuo et al 14 observed an outward movement of the parotid glands in the pretreatment CT images in 10 patients with head and neck cancer, pushed by enlarged neck lymph nodes. After 45 Gy of IMRT, nodal regression caused the parotid glands to shift inward into the high-dose area.…”

Section: -13mentioning

confidence: 99%